The invention relates to an electronic lock in accordance with the preamble of patent claim 1.
An electronic lock of this type is used in motor vehicles as an electronic ignition lock for operating an associated operating unit, such as an engine controlling means, an immobilizer or the like.
WO 95/09746 discloses a locking system for a motor vehicle, which comprises an electronic lock and an associated electronic key. The lock has a holder into which the key can be introduced. Situated in the lock is a switching element (merely indicated schematically) which can be actuated by the movement of the key as it is being introduced into the holder. The actuation of the switching element, whose switching signal can be interpreted as a “key inserted” signal, then switches on the normal operation of key and lock, the key in the holder exchanging at least one coding operating signal with the lock. After positive evaluation of the transmitted operating signal, i.e. if the key is the authorized one, release of the lock for movement of the holder by means of the key into at least one actuating position can be triggered. Starting up of the operating unit then takes place in the actuating position.
For security reasons, normal operation of key and lock has to be error-free. For this purpose, it is necessary to ensure that actuation of the switching element on introduction of the key into the holder is not error-prone. An idea to this effect cannot be inferred from WO 95/09746, since the switching element there can only be seen purely schematically.
Furthermore, it has turned out that operating states of the lock may occur in which the lock is released although the key has not been introduced, or not introduced completely, into the holder. In such an operating state it is possible for the holder to be moved into the actuation position. Manipulation of the switching element, and therefore of the “key inserted” signal, is not ruled out, in particular on removal of the key from the holder. As is immediately apparent, the security against theft is reduced as a result.
EP-A1-0 464 278 describes a lock which has a rotor which can be locked by means of magnetic tappets as tumblers. A key can be introduced into a holder of the rotor, the bit of the key being provided with a plurality of magnetic elements. If the key is the one associated with the lock, the magnetic elements correspond to the tappets, with the result that the effect of the magnetic force causes the tappets to be adjusted in order to release the movement of the rotor. At the same time, the tappets, as they are being adjusted, directly actuate associated switching elements which in turn enable an electric circuit in the motor vehicle.
Although the tumblers in this lock are moved magnetically, the lock otherwise functions essentially in the manner of a conventional, mechanical lock. The security of an electronic lock, in which a coded operating signal is exchanged with the key to bring about the release, is therefore not achieved here. Furthermore, it is disadvantageous that the magnetic tappet acts directly on the switching element. This firstly restricts the options for arranging the switching element in the lock. Secondly, the security against the switching element being manipulated is likewise not ensured. Consequently, EP-A1-0 464 278 does not impart more extensive ideas for the configuration of an electronic lock.